Demanding tenants purchase equipment for property care, Colorado

[Andrew Rinne]

What is the legality in Colorado Springs, CO of asking a tenant to purchase lawn care equipment (lawn mower, weed trimmer, rakes etc) to care for the owner's lawn? The lease agreement says: 

"Tenants are responsible for proper yard maintenance and upkeep including but not limited to mowing, watering, cleaning gutters, raking, and shoveling of sidewalks".

Are there any Colorado Springs or state of Colorado laws that would prevent an owner of a home from requiring the tenant purchases their own equipment?  I would be looking for specific laws or statutes that would prevent or allow this.

And if it is allowed, the wording on the lease is pretty vague. Who is to decide what makes maintenance of a yard "proper"?  What if the tenants think "proper" yard maintenance includes lovely, long, tall, bushy grass?  What if they don't like short grass?  What if the tenant has a disability that doesn't allow them to push a lawn mower? What if they would have to hire someone to do it in this case? So I'd also like to know what you all think about the wording of the lease as well and what the tenants might be able to get away with.

Thanks for taking the time to read and respond. One of my close friends is a pretty big player in your forums/is a moderator and he turned me on to you guys a few years ago and you've always been a real great source of info for my fiance and me. (As a side note, we finally have our first rental property in the Denver area! So excite!).

Cheers, ya'll.